Move general use gyro function get_sub to Submaster, make global Submasters object
- gyro's error subs now look like normal subs since they might reload and turn
into good subs.
- Also, add Submaster.fullsub which helps you make subs from channel names.

gyrocontroller: remap buttons, fix keep mode
Also, solo mode is now default, colors are brighter, numeric names for subs
are converted to subs with only that channel up, send zeroes when exiting

TkGyro: read subs from argv or stdin, cleanups
Some documentation and code reorganization/cleanups

TkGyro: "disable" text so it gets no events now
This fixes one of the bugs mentioned in the last TkGyro patch.

TkGyro added to gyrocontroller, seems mostly functional
Some bugs that still need to be fixed:
- It refuses to go full screen on my machine.
- Text in the middle can catch some events, we'd like it to pass them to
the rectangles under it.

SubClient created, keyboardcomposer and gyrocontroller use it now
Plus some minor cleanups in keyboardcomposer and gyrocontroller

gyrocontroller and Submaster.combine_subdict
gyrocontroller is not tested yet (nor does it have enough interface code
for that to be possible)